tough-pitch

from The Century Dictionary.

• noun Tough-pitch copper should show a silky fracture of light color and a close grain, and the cast ingot must, be free from any depression on the surface, as this would indicate an excess of dissolved oxid, due to insufficient poling. In tough-pitch copper the impurities present should all be In the oxidized condition, but no oxid of copper should be present. See overpole, also wire-bar pitch and plate-pitch.

from the GNU version of the Collaborative International Dictionary of English.

• noun The exact state or quality of texture and consistency of well reduced and refined copper.
• noun Copper so reduced; -- called also tough-cake.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The exact state or quality of texture and consistency of well reduced and refined copper.
• noun Copper so reduced; called also tough-cake.